Our research goals at UNSW were to develop a lime based binder and a hemp lime building material that could be manufactured in Australia for the mainstream Australian construction market.
When we began the building materials research at UNSW in 2000 it was with a commitment to developing an Australian building material using Australian grown hemp. It was also with the understanding that the hemp in the long run would need to be grown regionally in multiple regions of Australia to reduce the carbon footprint associated with freighting materials. The company’s Managing Director, Klara Marosszeky works closely with Australian farmers to support development of regional farming initiatives.
Although life cycle analysis of products is only starting to be broadly discussed, sustainable products need to consider all the steps in their manufacture and distribution.
The aims of our research were to develop a product and identify a process that would:
a) maximise the renewable resource in the composite material
b) minimise the energy-intensive heated and mined materials (limes) in the Binder
c) produce a building material with a low materials intensity and
d) incorporate process improvements based on the recommendations of leading researchers in Europe and the UK and on a lengthy period of field research in Australia on smaller trial builds.
Most commonly Binders used in Hemp Lime Construction combine industrial hemp with hydrated lime (heated to 800º approx.) which sets or cures through carbonation (it draws in carbon dioxide from the atmosphere) and hydraulic lime, which sets through hydration and is heated to up to 1200º C and cementitious materials such as pozzolans, volcanic ash, fly ash or other cements (heated up to temperatures of 1450º C). Across different manufacturers and the range of Hemp Lime products and applications available globally, the cementitious component of the Binders can be up to 50%.
Our research at the Australian Centre for Construction Innovation at UNSW resulted in the development of a Binder for Hemp Lime Construction in which by volume more than 55% of the building material is hemp. Sands that contribute to the material’s early set and strength are added to our product post manufacture to reduce the embodied energy and ecological footprint of our materials. Australian Hemp Masonry is amongst the most sustainable Hemp Lime Construction materials available globally.